Until Death
by caynaise
Summary: Thanks to her mother's reign of fear, Chisato fought alone in a world of demons and angels and other beings. But not anymore.


**Originally written for Bandori Rarepair Week 2019, Day 6: AU**

**This is a Shadowhunter Chronicles fusion AU rather than a crossover so uh, I hope it goes here? I have no idea if there's any overlap between the Bandori and Shadowhunters fandoms so like. If you're reading this and it makes no sense the only thing you need to know is that our girls are busy killing demons in this AU. That is all**

* * *

The first time Chisato sees her, she expects the usual reaction. She readies her defences, puts on a rehearsed smile and gets the "Nice to meet you"s out of the way. Professional, perfectly honed manners, hiding daggers that warn people not to come too close.

The other girl just eyes her with innocent curiosity, hands clasped in front of her, fiddling with her fingers.

Straightening up from a respectful bow, Chisato realises her mistake. "Ah, is this perhaps your first time in Idris?"

The girl nods. "My parents run the Tokyo Institute. I've lived there all my life."

"I see." That certainly does explain it. "I hope you enjoy your visit."

The next time they meet, Chisato, ever the fool, expects something to have changed since their first encounter. Tight-lipped smile, daggers at the ready.

"Oh, Shirasagi-san. Hello!"

What has she done to deserve such a welcoming gesture? She inclines her head. "Hello, Matsubara-san. Here for the meeting again?"

"Yes! Well, my parents are, anyway."

"Do you enjoy tagging along with them?"

"Ah . . ." The girl's eyes drop to her feet. "W-Well, actually, the pen you lent me last time—I accidentally held on to it. Um—here."

Chisato stares at her outstretched hand. "You came all the way here to return a pen?"

"Well . . ."

Chisato chuckles and pockets the retrieved object. "Thank you. I really hope it wasn't too much of an inconvenience."

"No, no! Besides, I don't get out much. It's a nice change of pace."

Chisato regards her with some curiosity of her own, now. "Perhaps you'd like to to familiarise yourself with the area, then. What do you say to a stroll through the city?"

"O-Oh, I'd be happy to do that! Thank you, Shirasagi-san."

Chisato turns on her heel, and looks back at her. "Please, call me Chisato."

It's then and there that she decides Kanon Matsubara isn't like the rest.

She takes Kanon to the various shops littered around the place, selling everything from clothes to antiques to weapons. Once they've exhausted their interest, she leads the way out of the city and up the grassy hill, and they find a shady spot under a clump of trees to sit down.

Kanon did hear about her fame among the Nephilim, of course. There's no way to conceal it from people, when your mother occupies the most powerful position in the Shadow World, and any enemies she made are rumoured to have met unspeakable fates.

How many of those rumours are true Chisato doesn't know, but sometimes she just wants a bit of normalcy in her life.

"Why didn't you keep your distance?" she asks Kanon, tucking her legs beneath her.

Kanon looks thoughtfully at the grass. "I guess I thought, well, you asked me if I hadn't been here before. No one else did."

_Oh_. Chisato doesn't let her shame show, but it nips at her conscience regardless. "That was only because . . ."

"You thought that was the only reason I could possibly not know? Yeah, I realised that afterwards."

"And yet you're sitting here talking to me." Chisato lets out an amused huff of laughter through her nose.

Kanon's lips curve upwards in a self-deprecating sort of way. "Yeah, I guess I am." She raises her eyes to meet Chisato's, gaze earnest. "I don't think you're a bad person, Chisato-chan."

* * *

Fast forward a few months, and Chisato and her little sister pack their bags and take a Portal to Tokyo. Being at home, in the bustling centre of Nephilim territory with every second person eyeing you as if they expect you to summon a demon in their house in the dead of night, is something she'd rather not deal with.

Kanon's family is welcoming, which doesn't surprise her in the least. Chisato keeps her room clean and helps with the dishes, trains like she would at home and for all intents and purposes, stays out of the way.

Kanon is clumsy, for a Shadowhunter, but she's strong. Chisato shows her where to put her feet, how to keep her balance while doing a million things with the twin blades in her hands.

Dual-wielding reminds her of playing the drums, Kanon says.

* * *

They take the oath when they're sixteen. Chisato will never forget the day Kanon came up to her in the Institute's library and asked.

"Chisato-chan, I've been thinking."

"What about?"

"About . . . what it's like to have someone who will fight alongside you, as a part of you, forever."

"I see." Chisato closed her book then, and looked away. "Is that what you want, Kanon?"

As always, Kanon wasn't deterred by her frigidness. After all, it was only fear that held her back, and Kanon knew that better than anyone.

"I used to think I'd never be able to go out there and face the demons, but when I'm with you . . . I feel like I can do anything."

"Kanon . . ."

"It's okay if you don't feel the same way."

She started to retreat, but Chisato took hold of her arm. "Don't be silly. I—Of course I do."

Kanon looked back at her with hopeful eyes. "You do? You'll . . . be my _parabatai_?"

A hush fell over them. Chisato took a breath, tremulous but decisive.

"Yes. I will, Kanon."

Their eyes meet over the rings of fire, stone all around them, and the runes that will bind their souls together, amplify their abilities, and in a way bring them closer than lovers until death, are branded into their skin.

Kanon's on her shoulder. Chisato's on her back, beside her shoulder blade.

They can never fall in love. That is the law, the only thing forbidden to them. But they _are _love. They live and breathe it, and it's entwined with their very souls.

Chisato doesn't remember ever baring so much of herself to another person.

* * *

A mishap comes in the form of a small lost child. The fluorescent lights of the local fairground blink and flash rainbow, the sounds of laughter and chatter fill the air, and the child that isn't a child weaves between the rides and the queues, and the lights shine in its pitch black demon eyes.

Chisato and Kanon exchange glances and tail the creature, past the excited kids and their tired parents, past the edges of the grounds, where the brightness abruptly cuts off and bushes and trees spring up in its stead.

Disguised though the demon may be, it's not stupid. It knows it's being followed.

The two of them have fought together long enough to dispense with wasteful words. A nod, a glance, and their plan of attack is laid out.

The element of surprise is crucial. They scale the trees, dropping down upon the creature in deadly silence, landing a few well-placed slashes that force it to morph back into its original, grotesque form, eyes lolling, tongue hanging out, claws bared in the moonlight.

It's like any other night—a little tiring, as slaughtering demons usually is, but manageable.

Until Chisato makes the leap from high above, blade shooting straight for the jugular, only to be met with a flash of silver and a scorching, burning pain across her stomach.

She doesn't remember much of the tussle after that point. The poison seeps into her system, and her hand shakes as it grips the blade, her vision coming and going in lengthening periods of blackness dissolving into reality and back again, until the numbness takes over, and even the thought of Kanon—her precious Kanon—fending off the demon on her own isn't enough to keep her consciousness from slipping away.

* * *

"Didn't you want to be an Iron Sister when you were little, Kanon?"

"Th-That was a long time ago."

The voices echo in Chisato's ears, sometimes coming from a great distance, other times seemingly directly from inside her. Those must be the hallucinations.

She wakes in a cold sweat, gasping and shaking.

Kanon is there by her side, anchoring her to the here and now. Of course she is.

Chisato isn't sure she can say the same of herself, where Kanon is concerned.

"Is it true?" she asks. "You wanted to be an Iron Sister?"

Kanon's gaze is soft, visibly forcing down the worry for Chisato's wellbeing as best she can. "That was . . . before I met you."

Chisato shifts in the infirmary bed, an involuntary groan dragged from her throat. "I have something of a hard time believing I had that significant an influence on your life. Is this really the life you want, Kanon? Fighting, wounding, instead of supporting the ones in battle, crafting the tools that will lead them to victory from a place far away from the field?"

Kanon is silent for a moment. Then she leans over the bed and takes Chisato's hand in both of her own, pressing it against her chest. "The runes of the Sisterhood would dissolve the ones that bind us. I . . . don't think I could live with that."

"But—"

"I understand now, why Shadowhunters see such glory in doing what we do. Even if I don't live to adulthood, even if I—I d-die forgotten and insignificant . . . a life without you is no life at all."

Despite the brave face she's trying so hard to put on, her hands are trembling. Chisato squeezes them, smiles reassuringly. "I can't make any grand promises, but I will honour our oath until the day we must part."

"That's all we can hope for, Chisato-chan. Thank you."

_No, thank _you, Chisato thinks, but no words can ever be sufficient, so she doesn't try to make them so.

She doesn't mention that she too has considered retiring from the frontlines to the Citadel where weapons are forged, if only for selfish reasons. She doesn't mention it, but for reasons not so selfish now.

"What do you say to a relaxing stroll tomorrow?" she suggests instead. "Through the Institute, that is. I think I've had quite enough of the outside for a month at the very least."

Kanon's laugh is like the wind chimes in the garden. "I would love that."


End file.
